Ugh! MBA or rMBP

I think I know the answer to this. I have a 2009 imac that has been abused by 5 years of high schoolers and 2 parents who really never took the time to understand the OS. There's 400+ gigs of stuff everywhere. No organization. 200 icons on the desktop. I want out!! I want a laptop of my own to start fresh. And, I'll actually try to understand how to properly organize all my stuff.

All I do is surf the net and email. I do have a T3i that I will uploading pics from but plan to get an external HD.
I'm also getting a router to take advantage of the new wifi. All I really want to do the majority of the time is surf the web while sitting in my recliner!

Which one should I get?

MBA 13
1.4
8
256

Or...

rMBP 13
2.6
8
128

Both are $1300. Mobility isn't a huge deal for me. My son's rMBP 15" is great!